Rickets

Plan

• Introduction – Defining the subject• (1): Pathogenesis• (2): Clinical Presentation and Diagnosis• (3): Treatment and Prevention• Conclusion

Defining the disease

• Rickets – word’s orginin is unknown– Maybe Rucket – to breath with difficulty, Dorset

word– Or Rhakhis – Spine, Rhachitis ‘’inflammation of

spine’’

Definition: A deficiency disease resulting from a lack of vitamin D or calcium and from insufficient exposure to sunlight, characterized by defective bone growth and occurring chiefly in children. Also called rachitis.

The American Heritage® Dictionary of the English Language

Normal Bone Processes

• Calcium and Phosphate– Constitutes the crystalline component of bone

• Deficiency leads to disease (i.e., Rickets and/or osteomalacia)

• Rickets: – Deficient mineralization at growth plate

• Osteomalacia: – impaired mineralization of the bone matrix.

• Open plates: Occur in Osteomalacia and rickets. • Closed plates: Happens in osteomalacia only!

Mineralization Defects

• Classified according to Predominant mineral deficiency:– 1) Phosphopenic (hypophosphatemic) rickets

• Primarily caused by phosphate deficiency

– 2) Calcipenic (hypocalcemic) rickets• Primarily caused by calcium deficiencyAssociated with decrease levels of phosphorus or calcium, respectively.

Pathogensis

• Growth Plate thickens:– Chondrocytes grow and hypertrophy– Vascular invasion of growth plate into primary bone

• Vascular invasion requires mineralization of the growth plate cartilage

• Can be delayed or prevent by deficiency of calcium or phosphorous

• In such circumstances growth plate cartilage accumulates and thickens. In addition, the chondrocytes of the growth plate becomes disorganised, losing their regular straight columned orientation.

The Pathogenic processes..

Osteoid Accumulation in metaphysisDecreased biochemical resistance of the invovled skeletal sites 2nd-ary inc- diameter of the growth plate. Compensatory mechanism due to decrease strenght by increase size Bone stability is compromised - if such condition does not improve, bowing occurs.

Pathogenesis (Normal) [2]

Proliferation of chondrocytesCalcification and vascular invasion

Reserve zone

Maturationzone

Proliferativezone

Hypertrophiczone

Primary spongiosa

2. Shapiro IM, Boyde A. Mineralization of normal and rachitic chick growth cartilage: vascular canals, cartilage calcification and osteogenesis. Scanning Microsc 1987; 1:599.

Pathogenesis (Rickets) [3-6]

Proliferation of chondrocytes Less calcification and vascular invasion

Thick + Disorganized cartilage

Hypertrophiczone

3. Lacey DL, Huffer WE. Studies on the pathogenesis of avian rickets. I. Changes in epiphyseal and metaphyseal vessels in hypocalcemic and hypophosphatemic rickets. Am J Pathol 1982; 109:288.4. Huffer WE, Lacey DL. Studies on the pathogenesis of avian rickets II. Necrosis of perforating epiphyseal vessels during recovery from rickets in chicks caused by vitamin D3 deficiency. Am J Pathol 1982; 109:302.5. Takechi M, Itakura C. Ultrastructural studies of the epiphyseal plate of chicks fed a vitamin D-deficient and low-calcium diet. J Comp Pathol 19956.. Rauch F. The rachitic bone. Endocr Dev 2003; 6:69.

Clinical manifestation

• Usually @ distal forearm, knee, and costochondral junctions.• Typically @Sites of rapid bone growth, where large quantities of calcium and phosphorus are required for mineralization.

Clinical Manifestations (Skeletal) [13]

1. Delay in closure of the fontanelles

2. Parietal & frontal bossing (due to excess osteoid)

3. Craniotabes ( soft skull bones)

4. Enlargement of the costochondral junction (rachitic rosary)

5. The development of Harrison sulcus ( caused by pull of the diaphragmatic attachments to the lower ribs)

6. Pigeon chest deformity (The weakened ribs bend inwards due to the pull of respiratory muscles, causing anterior protrusion of sternum)

7. Enlargement of the wrist + ankle & bowing of the distal radius & ulna

8. Genus Valgus (knocked), Genus Verus (bowleg), or Windswept deformity (combination of valgus deformity of 1 leg with varus deformity of the other leg)

Pictures from http://www.thachers.org

13. Misra M, Pacaud D, Petryk A, et al. Vitamin D deficiency in children and its management: review of current knowledge and recommendations. Pediatrics 2008; 122:398.

Clinical Manifestations (Extra-Skeletal)

• Depends upon the type of ricket

• Hypoplasia of the dental enamel is typical for hypocalcemic rickets, whereas abscesses of the teeth occur more often in phosphopenic rickets.

• Hypocalcemic seizures, decreased muscle tone leading to delayed motor milestones, recurrent infections, increased sweating

Clinical Manifestations • GENERAL Failure to thrive; Protuding abdomen;

Muscle weakness (especially proximal); Fractures• HEAD Craniotabes; Frontal bossing; Delayed

fontanelle closure; Delayed dentition; caries• CHEST Rachitic rosary; Harrison groove; or

Respiratory infections• BACK Scoliosis ,Kyphosis ,Lordosis• EXTREMITIES Enlargement of wrists and ankles;

Valgus or varus deformities Windswept deformity (combination of valgus deformity of 1 leg with varus deformity of the other leg); Anterior bowing of the tibia and femur; Leg pain.

• HYPOCALCEMIC SYMPTOMS Tetany, Seizures; Stridor due to laryngeal spasm

Chest radiograph of a patient with rickets, demonstrating a "rachitic rosary". Observe the opaque, bulbous indentations of the lung adjacent to the enlarged costochondral junctions (arrows).

Bilateral, symmetric bowing of the femurs and tibias.

Radiography

• Best visualised @ growth plate of rapidly growing bones.– Upper limb distal Ulna– Knee Metaphyses above and below

As disease progresses:

Disorganization of the growth plate becomes more apparent:1) with cupping,2) splaying,3) formation of cortical spurs4) stippling.

Fraying CuppingWidening of Growth plate

Radiological Manifestations

Normal

Metaphysis

Diaphysis

Epiphysis

Growth Plate

Normal Rickets

Widening of Growth Plate

Cupping

Cupping

Fraying

Healing Rickets

Periosteal reaction

Metaphyseal Sclerosis

Radiological Manifestations

Biochemical Findings in Rickets• Alkaline phosphatase: ↑in all forms of rickets

• Serum phosphorus: ↓ in both hypocalcemic and phosphopenic rickets (normal 5-7mg/dl)

• Serum Ca+2: ↓in hypocalcemic rickets (normal 9-11mg/dl)

• Serum PTH: ↑in hypocalcemic rickets, but normal in hypophosphatemic rickets

• 25-OH vitamin D reflect the amount of vitamin D stored in the body, and is ↓in vitamin D deficiency.

• 1,25-OH2 vitamin D can be↓, N or ↑in hypocalcemic rickets and usually is N or slightly ↑in phosphopenic rickets

Labs

• Alkaline phosphatase is increased markedly over the age-specific reference range.

• Excellent marker – participates in mineralization of bone and growth plate cartilage.

Evaluation

• A child with clinical signs of rickets should include dietary history with particular attention to given calcium and vitamin D intake

• Medication history• Measurement of serum creatinine and live

enzymes

Treatment of Rickets• EITHER: Vitamin D. stoss therapy: 300,000-600,000 IU orally or IM in 2-4

divided doses over one day

• OR: High dose vit D 2000-5000 IU orally for 4-6wks followed by 400 IU daily orally as maintenance

• OR: (5000-10,000 U) is given daily for 2-3 months until healing and alkaline phosphatase concentration is approaching to the normal

• Adequate dietary Calcium & phosphorus provided by milk, formula & other dairy products

• Symptomatic hypocalcaemia need IV CaCl as 20mg/kg or Calcium gluconate as 100mg/kg as a bolus, followed by oral calcium tapered over 2-6 weeks

PREVENTION

1.Exposure to sunlight (ultraviolet light)Early morning and evening 15 minutes per day

2. Lactating mothers should receive supplemention with milk or vitamin D to ensure prevention of rickets in their babies.3. Sun exposure to mothers

Prevention

4. Vitamin D supplementation (careful of toxicity): In prematures, twins and weak babies, give Vitamin D

800IU per day For term babies and infants the demand of Vitamin D is

400IU per day

Prevention

5. Calcium supplementation:

0.5-1gm/day, for premature, and weak babies

Outcome

• Good news:– Mostly reversible– Some deformities might persist

Conclusion

• Rickets refers to the changes at the growth plate caused by deficient mineralization of bone. Happens only before growth plates closure.

• 2 types of rickets• Skeletal findings + Extra skeletal findings• Certain radiographic findings

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